A popular device for handling large amounts of information in a data storage system is the automated cartridge library. Automated cartridge libraries store and manage large numbers of tape cassettes containing magnetic tape on which is recorded data. Typically an automated cartridge library comprises a tape library having arrays of uniquely identified cells, each cell being formed to contain a single tape cartridge. A robot assembly is operable within the tape library to locate a particular cell, retrieve a tape cartridge from the particular cell, convey the tape cartridge to a tape drive, and insert the tape cartridge into the tape drive. The tape drive then reads or writes data to the magnetic tape of the tape cartridge. In this way, a large number of tape cartridges are automatically accessible to a single tape drive. The operation of the automated cartridge library and the tape drive is typically controlled by a host computer communicating with a library server associated with the tape library.
A plurality of host computers typically communicate with the library server to access tape cartridges stored in the tape library. The host computers access the tape cartridges via the tape drives to read files stored on the tape cartridges and to write files to the tape cartridges.
Each of the host computers are configured to be connected to respective sets of tape drives associated with the tape library. For instance, a first host computer is configured to be connected to a first set of tape drives and a second host computer is configured to be connected to a second set of tape drives. Generally, the tape drives overlap in different tape drive sets associated with respective the host computers and the tape drive sets are not mutually exclusive.
To access a desired file, a host computer sends a request to the library server to retrieve the tape cartridge on which the desired file is stored. In response, the library server directs the robot assembly of the tape library to retrieve the desired tape cartridge from the array of tape cartridges and then mount it into a tape drive of the tape drive set associated with the host computer making the request. If the desired file is stored on more than one tape cartridge, then the library server directs the robot assembly to retrieve all of the tape cartridges storing the desired file and mount them into the tape drives associated with the host computer.
A disadvantage associated with prior art data storage systems is that configuring many host computers to be connected to their respective tape drives is unwieldy when simultaneous access to many tape drives is desired. What is needed is a method and system for dynamically selecting tape drives to connect with host computers.